The effect of spin exchange interaction on protein structural stability.

Partially charged chiral molecules act as spin filters, with preference for electron transport toward one type of spin ("up" or "down"), depending on their handedness. This effect is named the chiral induced spin selectivity (CISS) effect. A consequence of this phenomenon is spin polarization concomitant with electric polarization in chiral molecules. These findings were shown by adsorbing chiral molecules on magnetic surfaces and investigating the spin-exchange interaction between the surface and the chiral molecule. This field of study was developed using artificial chiral molecules. Here we used such magnetic surfaces to explore the importance of the intrinsic chiral properties of proteins in determining their stability. First, proteins were adsorbed on paramagnetic and ferromagnetic nanoparticles in a solution, and subsequently urea was gradually added to induce unfolding. The structural stability of proteins was assessed using two methods: bioluminescence measurements used to monitor the activity of the Luciferase enzyme, and fast spectroscopy detecting the distance between two chromophores implanted at the termini of a Barnase core. We found that interactions with magnetic materials altered the structural and functional resilience of the natively folded proteins, affecting their behavior under varying mild denaturing conditions. Minor structural disturbances at low urea concentrations were impeded in association with paramagnetic nanoparticles, whereas at higher urea concentrations, major structural deformation was hindered in association with ferromagnetic nanoparticles. These effects were attributed to spin exchange interactions due to differences in the magnetic imprinting properties of each type of nanoparticle. Additional measurements of proteins on macroscopic magnetic surfaces support this conclusion. The results imply a link between internal spin exchange interactions in a folded protein and its structural and functional integrity on magnetic surfaces. Together with the accumulating knowledge on CISS, our findings suggest that chirality and spin exchange interactions should be considered as additional factors governing protein structures.

Green energy by recoverable triple-oxide mesostructured perovskite photovoltaics.

Perovskite solar cells have developed into a promising branch of renewable energy. A combination of feasible manufacturing and renewable modules can offer an attractive advancement to this field. Herein, a screen-printed three-layered all-nanoparticle network was developed as a rigid framework for a perovskite active layer. This matrix enables perovskite to percolate and form a complementary photoactive network. Two porous conductive oxide layers, separated by a porous insulator, serve as a chemically stable substrate for the cells. Cells prepared using this scaffold structure demonstrated a power conversion efficiency of 11.08% with a high open-circuit voltage of 0.988 V. Being fully oxidized, the scaffold demonstrated a striking thermal and chemical stability, allowing for the removal of the perovskite while keeping the substrate intact. The application of a new perovskite in lieu of a degraded one exhibited a full regeneration of all photovoltaic performances. Exclusive recycling of the photoactive materials from solar cells paves a path for more sustainable green energy production in the future.

Magnetic oriented microparticles preparation.

Generally speaking, reaction platforms involving ferromagnetic surfaces, with a specific magnetic direction, are limited to the two dimensional regime, due to the nature of the magnetic phenomena. Here we show a method for preparing partially coated ferromagnetic microparticles with a distinct magnetic pole. This simple preparation method was presented previously [ 1 ] to demonstrate an application for enantiomeric separation. In this method article we show;•A simple method to a-symmetrically manipulate particle surfaces.•A generic way to synchronize a bare pole of ferromagnetic microparticles.•A simple and generic enantiomer purification technique.

Rapid Hydrogen Peroxide release from the coral Stylophora pistillata during feeding and in response to chemical and physical stimuli.

Corals make use of different chemical compounds during interactions with prey, predators and aggressors. Hydrogen Peroxide (H2O2) is produced and released by a wide range of organisms as part of their defense against grazers or pathogens. In coral reefs, the large fluxes and relatively long half-life of H2O2, make it a potentially important info-chemical or defense molecule. Here we describe a previously unstudied phenomenon of rapid H2O2 release from the reef-building coral Stylophora pistillata during feeding on zooplankton and in response to chemical and physical stimuli. Following stimuli, both symbiotic and bleached corals were found to rapidly release H2O2 to the surrounding water for a short period of time (few minutes). The H2O2 release was restricted to the site of stimulus, and an increase in physical stress and chemical stimuli concentration resulted in elevated H2O2 release. Omission of calcium (a key regulator of exocytotic processes) from the experimental medium inhibited H2O2 release. Hence we suggest that H2O2 is actively released in response to stimuli, rather than leaking passively from the coral tissue. We estimate that at the site of stimulus H2O2 can reach concentrations potentially high enough to deter predators or motile, potentially pathogenic, bacteria.

Has the clinical presentation and clinician's index of suspicion of cardiac tamponade changed over the past decade?

It remains unclear whether advances in the understanding of the pathophysiology and improvements in cardiovascular imaging over the years have impacted the clinician's recognition of cardiac tamponade (CT). We sought to evaluate signs and symptoms of CT in a present-day population and compare it to a similar group from a decade prior. We performed a retrospective analysis of two cohorts of patients presenting to a tertiary hospital with CT, all of whom underwent pericardial drainage (PD). Group 1 (Gp1) included subjects presenting from 1988 to 1991 and Group 2 (Gp2) included subjects from 2002 to 2005. Fifty-five patients comprised each group, with an average age of 55 years. Seventy-one percent of patients in Gp1 had identifiable cardiovascular symptoms 1 week prior to presentation, compared to 33% in Gp2. Dyspnea was the most common symptom in both groups, and was less frequent in Gp2. Compared with Gp1, chest pain, cough, and lethargy were also less frequent in Gp2. One day prior to PD, tachypnea and pulsus paradoxus were detected more frequently in Gp1 compared to Gp2. Large, circumferential pericardial effusions were the most frequent echocardiographic findings in both groups and the most common etiology of CT was malignancy in Gp1and postoperative bleeding in Gp2. Thus, the recognition of symptoms and physical signs in patients presenting with CT has changed over the past decade, as has etiology of pericardial effusions. However, the diagnosis of CT still remains delayed, and the present data emphasize the need for a heightened index of suspicion for recognizing this hemodynamically-important process.